High flow capacity filter

ABSTRACT

A filter element ( 202, 250 ) includes pleated filter media ( 26 ) having a plurality of pleats ( 28 ) in a closed annular loop having an outer perimeter ( 30 ) defined by a plurality of outer pleat tips ( 32 ), an inner perimeter ( 34 ) defined by a plurality of inner pleat tips ( 36 ), the loop having a hollow interior ( 38 ) extending along an axis ( 40 ), wherein fluid to be filtered flows laterally through the filter media and flows axially in the hollow interior ( 38 ). The filter element has an axial flow passage ( 56   a ) along the axis ( 40 ) and circumscribing the hollow interior ( 38 ) and has a flow perimeter ( 218 ) greater than the inner perimeter ( 34 ) of the filter element defined by the inner pleat tips ( 36 ), and in the preferred embodiment substantially the same as the outer perimeter ( 30 ) defined by the outer pleat tips ( 32 ), to provide axial flow ( 58 ) through the hollow interior ( 38 ) and additional axial flow ( 59  and  59   a ) through the axial ends ( 68 ) of the pleats.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation-in-part of U.S. application Ser. No.09/240,714, filed Jan. 29, 1999, now U.S. Pat. No. 6,149,700.

BACKGROUND AND SUMMARY

The invention relates to fluid filters, and more particularly toconstructions maximizing flow capacity and minimizing restriction.

There is continuing demand for increased flow capacity in the same oreven smaller size filters. This is particularly true in air cleanerdesigns for internal combustion engines, where engine compartment spaceis limited. A filter construction enabling higher capacity in the sameor less space provides competitive advantage and a space efficientfilter system.

A common air cleaner used in truck engines has a filter element providedby pleated filter media having a plurality of pleats in a closed loopconfiguration, typically annular, having an outer perimeter defined by aplurality of outer pleat tips, an inner perimeter defined by a pluralityof inner pleat tips, and a hollow interior extending along an axis. Theair typically flows laterally or radially inwardly through the filtermedia into the hollow interior and then axially outwardly through anoutlet flow tube to the combustion air intake of the engine. The outlettube has a diameter slightly smaller than the diameter of the hollowinterior between the inner pleat tips. A first end cap covers the axialends of the pleats at one axial end of the filter element and forms aradial seal with the outlet tube extending therethrough partially intothe hollow interior. Additionally or alternatively, the end cap forms anaxial seal with the housing containing the filter element. The end capis a resilient compressible material, to aid in forming the noted seals.The radial seal is formed by radially compressing the end cap materialbetween the outlet tube and the inner pleat tips or an inner linerextending therealong. The axial seal is formed by axially compressingthe end cap material between the axial ends of the pleats and the axialend of the housing containing the filter element. A second end capcovers the axial ends of the pleats at the other axial end of the filterelement and may span the hollow interior to close same, or such hollowinterior may be closed by a portion of the housing extending thereinto.The flow capacity of the filter is affected by various factors,including restrictions, such as the size of the outlet opening throughthe noted outlet tube at the axial end of the filter.

The invention of the noted parent application increases flow capacity byenabling enlargement of the outlet flow passage, to lower the notedrestriction to flow. The increased outlet size of the filter element andlowered restriction is accomplished while still maintaining or evenincreasing the amount of filter media and while also staying within thesame package or housing size. As noted above, in the prior art, thelargest diameter outlet from the filter element is limited toapproximately the size of the diameter of the hollow interior defined bythe inner pleat tips. In the preferred embodiment of the parentinvention, the end cap encloses only the outer edges of the axial endsof the pleats, and has an inner diameter larger than the diameter of thehollow interior defined by the inner pleat tips. The enlarged innerdiameter of the end cap forms a radial seal with an enlarged outlet tubehaving a diameter greater than the diameter of the hollow interiordefined by the inner pleat tips. A radial seal is formed between theenlarged diameter outlet tube and the enlarged inner diameter end cap ata location along the axial ends of the pleats between the inner pleattips and the outer pleat tips. An outer liner circumscribes the filterelement along the outer pleat tips and extends beyond the axial endthereof into the end cap and provides support for the noted radial seal,i.e. the end cap material is radially compressed between the outlet tubeand the outer liner. The outlet flow passage from the filter element isnow the inside diameter of the end cap rather than the diameter of thehollow interior defined by the inner pleat tips. Fluid passing throughthe filter media can now also travel axially between the pleats as wellas axially through the hollow interior defined by the inner pleat tips.As a result of such construction, fluid flow restriction is reduced, andthe radial depth of the pleat is no longer limited to a specific outlettube diameter. Instead, the radial depth of the pleat can theoreticallyextend all the way to the axial center line of the filter, allowingmaximization of filter media area within a given package or housingsize. The parent invention may also be used for opposite direction flowfilters, in which case enlargement of the inlet flow passage is enabled,to reduce inlet flow restriction.

The present invention further increases flow capacity by enablingfurther enlargement of the outlet flow passage, to further lower thenoted restriction to flow. The further increased outlet size of thefilter element and the further lowered restriction is accomplished whilestill maintaining or even increasing the amount of filter media andwhile also staying within the same package or housing size. In thepresent invention, the largest diameter outlet from the filter elementis not limited to the size of the diameter of the hollow interiordefined by the inner pleat tips, nor limited to the inner diameter ofthe end cap even if the latter is enlarged in accordance with the notedparent invention. The present invention enables the filter outlet tohave a diameter substantially as large as the outer diameter of thefilter element at the outer pleat tips. The invention may also be usedfor opposite direction flow filters, in which case maximized enlargementof the inlet flow passage is enabled, to minimize inlet flowrestriction.

BRIEF DESCRIPTION OF THE DRAWINGS Parent Invention

FIG. 1 is taken from the above noted parent U.S. application Ser. No.09/240,714, filed Jan. 29, 1999, and is a side elevation view of afilter constructed in accordance with the parent invention.

FIG. 2 is a sectional view taken along line 2—2 of FIG. 1.

FIG. 3 is an isometric view of a portion of the filter element of FIG.2.

FIG. 4 is a sectional view taken along line 4—4 of FIG. 3.

FIG. 5 is a sectional view taken along line 5—5 of FIG. 4.

FIG. 6 is a sectional view taken along line 6—6 of FIG. 4

FIG. 7 is a sectional view taken along line 7—7 of FIG. 4.

FIG. 8 is an enlarged view of a portion of the structure of FIG. 3,partially cut away.

FIG. 9 is a view like FIG. 8, with a further portion cut away.

FIG. 10 is a view like a portion of FIG. 2, and shows an alternateembodiment.

FIG. 11 shows a mold for molding or potting an end cap onto pleatedfilter media of the filter element.

Present Invention

FIG. 12 is a sectional view similar to FIG. 2 but showing a filterelement in accordance with the present invention.

FIG. 13 is like FIG. 11 but shows a mold for molding or potting an endcap onto pleated filter media of the filter element of the presentinvention.

FIG. 14 is like FIG. 12 and shows another embodiment.

DETAILED DESCRIPTION Parent Invention

FIGS. 1 and 2 show a filter 20 including a filter element 22 containedwithin a housing 24. Filter element 22 is provided by pleated filtermedia 26, FIG. 2, having a plurality of pleats 28, FIGS. 5-9, in aclosed loop, typically an annulus, having an outer perimeter 30 definedby a plurality of outer pleat tips 32, and an inner perimeter 34 definedby a plurality of inner pleat tips 36. The annular closed loop has ahollow interior 38 extending along an axis 40. Housing 24 is typicallycylindrical and is provided by housing sections 42 and 44 mounted toeach other in conventional manner such as by overcenter spring clip typeclamps such as 46, or in other suitable manner. The housing has an inlet50 admitting inlet fluid, such as air or liquid, radially and/ortangentially into annular space 52 within the housing around filterelement 22. The housing may include an interior dam or deflectionsurface 54 for blocking direct impact against filter element 22 and/orfor directing flow, for example in a spiral or toroidal pattern. Thefluid flows laterally or radially inwardly through filter media 26 intohollow interior 38, and then the clean fluid flows axially rightwardlyin FIG. 2 in hollow interior 38 along flow passage 56 as shown at arrows58, 59.

Flow passage 56 extending along axis 40 circumscribes hollow interior 38and has a flow perimeter 60 greater than inner perimeter 34 defined byinner pleat tips 36, to be described. Flow perimeter 60 is less thanouter perimeter 30 defined by outer pleat tips 32. Inner perimeter 34defines and bounds a first cross-sectional area. Flow perimeter 60defines and bounds a second cross-sectional area. The second crosssectional area is greater than the first cross-sectional area. Outerperimeter 30 defines and bounds a third cross-sectional area. The secondcross-sectional area is less than the third cross-sectional area.

Filter element 22 has first and second axial ends 62 and 64. Axial end62 is open, FIG. 3, and provides axial flow passage 56 therethrough. Anend cap 66 of soft resilient compressible material, such as foamedpotted urethane, axially abutts the axial ends 68 of the pleats. End cap66 has an inner perimeter 70, FIGS. 3 and 4, greater than innerperimeter 34 defined by inner pleat tips 36. End cap 66 partially coversthe axial ends 68 of the pleats such that the laterally outward portions72 of the axial ends of the pleats are covered by end cap 66 but not thelaterally inward portions 74 of the axial ends of the pleats, such thatthe laterally inward portions 74 of the axial ends of the pleats areuncovered and exposed at axial end 62 of filter element 22, FIGS. 8 and9. Second axial end 64 of filter element 22 is closed. A second end cap76, FIG. 2, of soft compressible resilient material, such as foamedpotted urethane, is provided at second end 64 of the filter element andcompletely covers the axial ends 78 of the pleats including the outerpleat tips and the inner pleat tips at axial end 64. End cap 76 alsoincludes a central section 80 spanning and completely covering hollowinterior 38 of filter element 22 at axial end 64 of the filter element.Housing section 44 includes an annular interior sidewall 82 extendingpartially axially into the housing to locate and retain filter element22 at axial end 64. In other embodiments, central section 80 of end cap76 is omitted, and a portion of housing section 44 extends into hollowinterior 38 of filter element 22 to close axial end 64 of the filterelement and to position axial end 64 of the filter element within thehousing. End cap 76 includes an annular ridge 84 engaging axial endwall85 of housing section 44 and slightly axially compressed there againstto further aid in retention of filter element 22 within the housing andto accommodate axial tolerances. End cap 66 also includes an annularridge 86 engaging axial endwall 88 of housing section 42 and slightlyradially compressed there against to aid in retaining filter element 22within the housing and to accommodate axial tolerances and also toprovide an axial seal to prevent bypass of dirty air from annularchamber 52 around axial end 62 of the filter element. Axial endwall 88of housing section 42 has an outlet flow tube 90 extending therethrough.In addition to or alternatively to the axial seal at 86, end cap 66provides a radial seal against outlet flow tube 90, to be described.

End cap 66 has a sidewall 92, FIGS. 2 and 4, extending axially awayaxial ends 68 of pleats 28 at axial end 62 of filter element 22. Thesidewall has an inner perimeter 70, as above noted, and an outerperimeter 94. As noted above, inner perimeter 70 of sidewall 92 isgreater than inner perimeter 34 of filter element 22 defined by innerpleat tips 36. Inner perimeter 70 of sidewall 92 of end cap 66 is lessthan outer perimeter 30 of filter element 22 defined by outer pleat tips32. Outer perimeter 94 of sidewall 92 of end cap 66 is greater thanouter perimeter 30 of filter element 22 defined by outer pleat tips 32.Flow tube 90 has an inner section 96 axially facing the axial ends 68 ofpleats 28. Inner section 96 of flow tube 90 has an inner perimeter 98and an outer perimeter 100. Outer perimeter 100 is greater than innerperimeter 70 of sidewall 92 of end cap 66, such that as filter element22 at end cap 66 is axially slid rightwardly over inner section 96 offlow tube 90, end cap 66 is radially compressed to expand innerperimeter 70 along outer sidewall 100 of flow tube inner section 96 toeffect the noted radial seal. Inner perimeter 70 of end cap 66 ispreferably stepped, as shown at steps 71, FIG. 8, to have slightlyprogressively decreasing diameters from right to left as viewed in FIGS.8 and 2, to receive and guide inner section 96 of flow tube 90therealong and increase radial sealing pressure. End cap 66circumscribes inner section 96 of flow tube 90 and bears radially thereagainst in sealing relation to form the noted radial seal thereat.Endwall 88 of housing section 42 axially faces axial ends 68 of pleats28, and end cap 66 also bears axially against endwall 88 in sealingrelation to form the noted axial seal thereat.

An outer liner 102, FIGS. 2 and 4, provided by an expanded wire mesh orscreen or perforated metal, circumscribes filter element 22 along outerpleat tips 32 and has an axial end section 104 extending axially beyondthe axial ends 68 of pleats 28. As above described, flow tube 90communicates with hollow interior 38 of the filter element along flowpassage 56 and extends axially from the axial end of the filter element.End cap 66 at the axial end of the filter element bears radially betweenand is radially compressed between and against section 104 of outerliner 102 and inner section 96 of flow tube 90. Outer liner 102 extendsaxially at 104 into end cap 66 and is potted therein during the moldingprocess, to be described. As noted above, sidewall 92 of end cap 66extends axially away from the axial ends 68 of pleats 28 at the axialend of the filter element. Outer perimeter 94 of the end cap sidewallcircumscribes outer liner section 104.

Pleats 28 have pairs of walls defining axially extending interiorchannels 106, FIG. 7, and axially extending exterior channels 108. Thewalls of the pleats defining the exterior channels 108 are sealed toeach other near axial end 62 of the filter element by heat seal bondingalong glue strips such as 110, as known in the art, for example asdisclosed in U.S. Pat. No. 5,106,397, incorporated herein by reference.This prevents bypass of dirty air around the axial ends of the pleats atinner exposed portions 74, FIGS. 8 and 9. Fluid such as air flowingradially inwardly through the filter media as shown at 112, FIG. 4, mustflow through the sidewalls of pleats 28 before such fluid can flowaxially as shown at arrows 58, 59. Some of such air can flow axiallyrightwardly in FIG. 4 as shown at arrow 59 axially along interiorchannels 106, and the balance of the air continues radially inwardly asshown at arrow 114 and then flows axially as shown at arrow 58. Theaxial ends of exterior channels 108 at the axial end of the filterelement are blocked by the noted seal bonding along adhesive strips 110.Fluid flowing through the filter element is forced to pass from exteriorchannels 108 to interior channels 106. FIGS. 6 and 9 show the sealbonded adhesive 110 extending in exterior channels 108 all the way frominner pleat tips 36 to outer pleat tips 32 as idealized. If the sealbond does extend all the way from inner pleat tip 36 to outer pleat tip32, then the shape of the interior channel 106 at outer pleat tip 32will generally be more rounded and the walls of pleats 28 formingexterior channels 108 at outer pleat tips 32 will usually be closertogether. In an alternative, the adhesive seal bond in exterior channels108 may extend from inner pleat tips 36 only partially towards outerpleat tips 32, and the outer portions of exterior channels 108 areblocked at the axial end of the filter element by end cap 66. During themolding potting process, to be described, the liquid castable materialinto which the pleated filter media is dipped will foam up a shortdistance axially into the channels between the pleats, as shown at innersection 116, FIGS. 4, 8, 9, of the end cap which has migrated a distance118, FIG. 4, between the pleats. The spacing of glue strips 110 on thepleats from the axial ends 68 of the pleats may be adjusted as desiredin standard glue seal strip applicator machines. Preferably, glue sealstrips 110 are spaced from axial ends 68 of the pleats by a smalldistance 118 to enable a slight deformation of the axial ends 68 of thepleats by a dam in the mold during the molding potting process, to keepthe liquid castable material of the end cap from flowing radiallyinwardly onto inner portions 74 of the pleat ends which are desired tobe exposed, which molding process and dam are to be described.Alternatively, seal glue strips 110 may be applied at axial ends 68 ofthe pleats, without gap 118 therebetween.

FIG. 11 shows a mold 120 for molding or potting end cap 66 onto pleatedfilter media 26 of the filter element. The mold has a trough 122extending along an annular first perimeter and holding liquid castablematerial, such as urethane, therein into which axial ends 68 of pleats28 are dipped. The mold has an insert 124 with an upstanding dam 126extending along a second annular perimeter circumscribed by the notedannular perimeter of trough 122. Dam 126 engages axial ends 68 of thepleats between outer pleat tips 32 and inner pleat tips 36 and impedesflow of liquid castable material laterally radially inwardly towardsinner pleat tips 36. Trough 122 partially spans axial ends 68 of thepleats such that the laterally outward portions 72 of the axial ends ofthe pleats are covered by the liquid castable material but not thelaterally inward portions 74 of the pleats, such that laterally outwardportions 72 of the axial ends of the pleats are covered by end cap 66,and laterally inward portions 74 of the axial ends of the pleats areuncovered by end cap 66 and are left exposed. It is preferred that thepleated filter media be dipped into the liquid castable material in themold by lowering the pleated filter media downwardly until axial ends 68of the pleats are engaged by dam 126, and then pushing the pleatedfilter media further slightly downwardly against the dam such that thedam slightly deforms axial ends 68 of the pleats at such engagementpoint which in turn pushes the pleat sidewalls forming the notedchannels slightly laterally to further block the channels and furtherimpede flow of liquid castable material laterally inwardly towards innerpleat tips 36. Trough 122 is bounded by an outer perimeter 126 and aninner perimeter 128. Outer perimeter 126 of trough 122 is greater thanouter perimeter 30 of the filter element defined by outer pleat tips 32.Inner perimeter 128 of trough 122 is less than outer perimeter 30 of thefilter element. Inner perimeter 128 of trough 122 is greater than innerperimeter 34 of the filter element defined by inner pleat tips 36. Thenoted second perimeter of the mold at annular dam 126 is less than orequal to inner perimeter 128 of trough 122.

As noted, the method for molding end cap 66 onto pleated filter media 26involves dipping axial ends 68 of the pleats into liquid castablematerial in trough 122 of mold 120, and engaging axial ends 68 of thepleats against dam 126 at a location between outer pleat tips 32 andinner pleat tips 36 such that dam 126 impedes flow of the liquidcastable material laterally inwardly towards inner pleat tips 36. Trough122 is provided and aligned such that it partially spans axial ends 68of the pleats such that the laterally outward portions 72 of the axialends of the pleats are covered by the liquid castable material duringdipping, but not the laterally inward portions 74 of the axial ends ofthe pleats. Further in accordance with the described method, laterallyinward flow of the liquid castable material is impeded along the axialends of the pleats toward inner pleat tips 36 by providing and aligningdam 126 to engage axial ends 68 of the pleats between outer pleat tips32 and inner pleat tips 36, such that laterally outward portions 72 ofthe axial ends of the pleats are covered by end cap 66, and laterallyinward portion 74 of the axial ends of the pleats are uncovered by endcap 66 and are left exposed. Trough 122 and filter element 22 arealigned during the noted dipping such that outer perimeter 126 of trough122 circumscribes outer perimeter 30 of the filter element defined byouter pleat tips 32, and inner perimeter 128 of trough 122 circumscribesinner perimeter 26 of the filter element defined by inner pleats 36.

FIG. 10 shows an alternate embodiment wherein outlet flow tube 90 a hasan outer section 90 b of reduced diameter to accommodate enginecompartment size and location requirements, yet maintaining an increaseddiameter inner section 90 c maintaining the increased diameter andperimeter flow passage 56 including axial fluid flow at 58 and the extraaxial fluid flow at 59, FIGS. 4 and 10. The spacing of axial endwall 88of housing section 42 from axial ends 68 of the filter media pleatsprovides a plenum 130 accommodating the extra flow and reducingrestriction.

The described filter construction was developed for air filters, thoughmay be used for other fluids such as liquid. In the disclosedembodiment, fluid to be filtered flows laterally inwardly through thefilter media from the outer perimeter to the inner perimeter and thenflows axially in the hollow interior, such that flow passage 56 is anoutlet flow passage. Alternatively, fluid to be filtered may flowaxially in hollow interior 38 and then flow laterally outwardly throughthe filter media from the inner perimeter to the outer perimeter, inwhich case flow passage 56 is an inlet flow passage. In otheralternatives, metal end caps are used instead of urethane end caps, orvarious combinations of materials are used for the end caps. In furtherembodiments, an inner liner may be added along inner pleat tips 36. Infurther alternatives, outer section 90 b, FIG. 10, of the flow tube hasa larger inner diameter than inner section 90 c.

Present Invention

FIGS. 12-14 show the present invention, and use like reference numeralsfrom above where appropriate to facilitate understanding.

FIG. 12 shows a filter element 202 for mounting in housing 24. Filterelement 202 is provided by the noted pleated filter media 26 having aplurality of pleats 28 in a closed loop, typically an annulus, having anouter perimeter 30 defined by a plurality of outer pleat tips 32, and aninner perimeter 34 defined by a plurality of inner pleat tips 36. Theannular closed loop has a hollow interior 38 extending along axis 40.Fluid to be filtered flows laterally or radially through filter media26, and flows axially in hollow interior 38. The filter element has anaxial flow passage 56 a extending along axis 40 and circumscribinghollow interior 38 and having a flow perimeter as shown at diameter 204greater than inner perimeter 34 as shown at diameter 206. Filter element202 has first and second axial ends 62 and 64. First axial end 62 isopen and provides the noted axial flow passage 56 a therethrough. An endcap 208 of soft compressible resilient material, such as foamed pottedurethane, is provided around outer pleat tips 32 at axial end 62 and hasan outer perimeter 210 as shown at diameter 212 greater than the outerperimeter 30 of the outer pleat tips 32 as shown at diameter 204 andforming an outer sealing surface 214 external to axial flow passage 56 aand engaging inner surface 43 of housing section 42 in radiallycompressed sealing relation. The axial end 216 of end cap 208 may or maynot engage axial endwall 88 of housing section 42 in axially compressedor noncompressed relation. Sealing is accomplished by the radial sealprovided by radial compression of end cap 208 between section 104 ofouter liner 102 and inner facing surface 43 of the housing and/or theaxial seal provided by axial compression of end cap 208 against axialendwall 88 of the housing. Section 104 of outer support liner 102provides a support backing for compression of radial sealing of end cap208 there against, as above. Second end cap 76 is provided at second end64 of the filter element and completely covers the axial ends of thepleats including the outer pleat tips and the inner pleat tips. Asabove, end cap 76 also includes central section 80 spanning andcompletely covering the hollow interior of the filter element andclosing same.

Outer sealing surface 214 of end cap 208 at outer perimeter 210 facesaway from axial flow passage 56 a and radially outwardly relative toaxis 40. End cap 208 has an inner perimeter 218 as shown at diameter 204substantially equal to the outer perimeter 30 at outer pleat tips 32 asalso shown at diameter 204. The outlet flow tube of the housing, shownat 90 in FIG. 2, is enlarged as shown at 90 d in FIG. 12 to the noteddiameter 204. This further increases and maximizes flow capacity, andfurther reduces and minimizes flow restriction. Fluid flows not only atarrows 58 and 59 as above, but also at arrow 59 a through the laterallyoutward portions 72, FIGS. 8, 9, 4, of the axial ends of the pleats,axially through channels 106, FIGS. 6, 7.

End cap 208 encapsulates outer pleat tips 32 and outer support liner102. End cap 208 has a major margin 220 extending radially outwardlyaway from outer support liner 102 to outer perimeter 210 of end cap 208.End cap 208 has a minor margin 222 extending radially inwardly fromouter support liner 102 to the inner perimeter 218 of the end cap. Minormargin 222 encapsulates outer pleat tips 32. The radial or lateralextension of major margin 220 is substantially longer than the radial orlateral extension of minor margin 222. Inner perimeter 218 of end cap208 is substantially equal to outer perimeter 30 at outer pleat tips 32,the difference being the length or radial extension of minor margin 222.

Inner perimeter 34 at inner pleat tips 36 defines and bounds a firstcross sectional area. Inner perimeter 218 of end cap 208 defines theflow perimeter as shown at diameter 204 of axial flow passage 56 a.Inner perimeter 218 of end cap 208 defines and bounds a secondcross-sectional area. Outer perimeter 30 at outer pleat tips 32 definesand bounds a third cross-sectional area. The difference between thenoted first and second cross-sectional areas is substantially greaterthan the difference between the noted second and third cross-sectionalareas.

As above, fluid to be filtered flows laterally inwardly through filtermedia 26 from outer perimeter 30 at outer pleat tips 32 to innerperimeter 34 at inner pleat tips 36 and then flows axially in hollowinterior 38 and then out through flow passage 56 a and housing outlettube 90 d. Flow passage 56 a is thus an outlet flow passage. In analternate embodiment, fluid to be filtered flows axially into thehousing through flow tube 90 d then axially along flow passage 56 a intohollow interior 38 and then flows laterally outwardly through filtermedia 26 from inner perimeter 34 at inner pleat tips 36 to outerperimeter 30 at outer pleat tips 32. In this embodiment, flow passage 56a is an inlet flow passage. The present invention provides the axialflow as shown at arrow 58 in FIG. 4 and the axial flow as shown at arrow59, and further provides additional axial flow as shown at arrow 59 a inFIG. 12. The latter is due to the substantial removal of the radialextension of the end cap 208 from the axial ends 68 of the pleats incombination with moving the sealing function to outer periphery 210and/or 216, FIG. 12, compared to the end cap of FIGS. 2 and 4 withinwardly facing radial sealing surface 70 and/or axial sealing surface86, and end cap portion 116 covering the axial ends of the pleats andblocking otherwise available flow passage area. The extra flow enabledby the present invention at arrow 59 a in FIG. 12 is in addition to theextra flow 59 provided by the parent invention. The present inventionthus further increases and maximizes flow capacity, and further reducesand minimizes flow restriction.

FIG. 13 is similar to FIG. 11 and shows a mold 230 for molding orpotting end cap 208 onto pleated filter media 26 of the filter element.The mold has a trough 232 extending along an annulus and holding liquidcastable material, such as urethane, therein into which axial ends 68 ofpleats 28 are dipped. Annular trough 232 has an outer perimeter 234defining outer perimeter 210 of end cap 208, and an inner perimeter 236defining inner perimeter 218 of end cap 208. It is preferred that therebe a minimal gap 238 between inner perimeter 236 and outer support liner102 of the filter element to encapsulate end section 104 of liner 102and to encapsulate outer pleat tips 32 along their axial ends 68. It ispreferred that gap 238 be kept to a minimum, such that inner perimeter236 is substantially equal to perimeter 30. In other embodiments, theradial length of gap 238 is zero, i.e. there is no gap between innerperimeter 236 and outer liner 102. The mold has an insert 240 with anupstanding dam 242 extending along inner perimeter 236 and having anaxial end engaging axial ends 68 of the pleats and impeding flow ofliquid castable material laterally radially inwardly towards inner pleattips 36. The pleated filter media is dipped into the liquid castablematerial in the mold by lowering the pleated filter media downwardlyuntil axial ends 68 of the pleats are engaged by dam 242, and thenpushing the pleated filter media further slightly downwardly against thedam such that the dam slightly deforms axial ends 68 of the pleats atsuch engagement point which in turn pushes the pleat sidewalls formingthe noted channels slightly laterally to further block the channels andfurther impede flow of liquid castable material laterally inwardlytowards inner pleat tips 36.

FIG. 14 is like FIG. 12 and shows another embodiment and uses likereference numerals where appropriate to facilitate understanding. Filterelement 250 has an end cap 252 with a metal support extension member 254embedded therein during the noted molding. The support extension memberhas a first leg 256 along outer support liner 102 at outer pleat tip 32,a second leg 258 extending radially outwardly from leg 256, and a thirdleg 260 providing a support backing for compression of sealing portion262 of the end cap there against. Sealing portion 262 is between leg 260and outer sealing surface 264 and is spaced radially outwardly of outerpleat tips 32 by a radial gap 266 between legs 256 and 260. Leg 258 hasfirst and second sides 268 and 270 facing axially in opposite directionsand defining, in combination with legs 256 and 260, the noted radial gap266. End cap 252 has a first portion 272 in radial gap 266, and a secondportion 262 radially outwardly thereof and providing the noted sealingportion. Second side 270 of leg 258 faces an open radial gap 274 betweenouter pleat tips 32 and portion 262 of end cap 252. Open radial gap 274is unfilled by the potting material of end cap 252. Legs 256, 258, 260define a U-shaped support extension member 254, second leg 258 being thebight of the U, and first and third legs 256 and 260 extending axiallyand generally parallel to one another.

It is recognized that various equivalents, alternatives andmodifications are possible within the scope of the appended claims.

What is claimed is:
 1. A filter element comprising pleated filter mediahaving a plurality of pleats in a closed loop having an outer perimeterdefined by a plurality of outer pleat tips, and an inner perimeterdefined by a plurality of inner pleat tips, said loop having a hollowinterior extending along a given axis, wherein fluid to be filteredflows laterally through said filter media, and flows axially in saidhollow interior, said filter element having an axial flow passageextending along said axis and circumscribing said hollow interior andhaving a flow perimeter greater than said inner perimeter, said filterelement having first and second axial ends, said first axial end beingopen and providing said axial flow passage therethrough, and an end caparound said outer pleat tips at said first axial end and having an outerperimeter greater than said outer perimeter of said outer pleat tips andforming an outer sealing surface external to said axial flow passage. 2.The invention according to claim 1 wherein said outer sealing surfacefaces away from said axial flow passage and radially outwardly relativeto said axis.
 3. The invention according to claim 1 wherein said end caphas an inner perimeter substantially equal to said outer perimeter ofsaid outer pleat tips.
 4. The invention according to claim 1 comprisingan outer support liner around said filter element at said outer pleattips, and wherein said end cap encapsulates said outer pleat tips andsaid outer support liner, said end cap having a major margin extendingradially outwardly away from said outer support liner to said outerperimeter of said end cap.
 5. The invention according to claim 4 whereinsaid end cap has a minor margin extending radially inwardly from saidouter support liner to the inner perimeter of said end cap, said minormargin encapsulating said outer pleat tips.
 6. The invention accordingto claim 5 wherein the radial extension of said major margin is longerthan the radial extension of said minor margin.
 7. The inventionaccording to claim 6 wherein the radial extension of said major marginis substantially longer than the radial extension of said minor margin,and wherein said inner perimeter of said end cap is substantially equalto said outer perimeter of said outer pleat tips, the difference beingthe length of said radial extension of said minor margin.
 8. Theinvention according to claim 1 wherein said inner perimeter of saidinner pleat tips defines and bounds a first cross-sectional area, saidend cap has an inner perimeter defining said flow perimeter, said innerperimeter of said end cap defines and bounds a second cross-sectionalarea, said outer perimeter of said outer pleat tips defines and bounds athird cross-sectional area, and wherein the difference between saidfirst and second cross-sectional areas is substantially greater than thedifference between said second and third cross-sectional areas.
 9. Theinvention according to claim 1 comprising a second end cap at saidsecond axial end of said filter element completely covering the axialends of said pleats including said outer pleat tips and said inner pleattips at said second axial end.
 10. The invention according to claim 9wherein said second end cap also spans and completely covers said hollowinterior at said second axial end of said filter element.
 11. Theinvention according to claim 1 wherein said fluid to be filtered flowslaterally inwardly through said filter media from said outer perimeterof said outer pleat tips to said inner perimeter of said inner pleattips and then flows axially in said hollow interior, wherein said flowpassage is an outlet flow passage.
 12. The invention according to claim1 wherein said fluid to be filtered flows axially in said hollowinterior and then flows laterally outwardly through said filter mediafrom said inner perimeter of said inner pleat tips to said outerperimeter of said outer pleat tips, wherein said flow passage is aninlet flow passage.
 13. The invention according to claim 1 wherein saidclosed loop is annular.
 14. The invention according to claim 1comprising a support extension member in said end cap, said supportextension member having a first leg at said outer pleat tips, a secondleg extending radially outwardly from said first leg, and a third leg atthe outer end of said second leg, said third leg providing a supportbacking for compression of a sealing portion of said end cap thereagainst, said sealing portion being between said third leg and saidouter sealing surface and spaced radially outwardly of said outer pleattips by a radial gap between said first and third legs.
 15. Theinvention according to claim 14 wherein said second leg has first andsecond sides facing axially in opposite directions and defining, incombination with said first and third legs, said radial gap, and whereinsaid end cap has a first portion in said radial gap, and a secondportion radially outwardly thereof and providing said sealing portion.16. The invention according to claim 15 wherein said second side of saidsecond leg faces an open radial gap between said outer pleat tips andsaid second portion of said end cap, said open radial gap being unfilledby said end cap.
 17. The invention according to claim 14 wherein saidfirst, second and third legs define a U-shaped said support extensionmember, said second leg being the bight of the U, said first and thirdlegs extending axially and generally parallel to one another.